[Z06] 02 Z06 Rear Diff Chatter Problem
Thread Starter
Melting Slicks
Joined: Dec 2002
Posts: 2,061
Likes: 1
From: Valley Village CA
02 Z06 Rear Diff Chatter Problem
I had my rear diff fluid changed last April. Used Redline 75/90w and 1.5 bottle of Redline friction modifier. The car is not a daily driver and has not had even 1000 miles since then but has developed a rear diff chatter when turning right clutch in and gliding around a turn.Today I had the fluid flushed and now used the GM OEM 75/90w fluid with 2 bottles of the GM friction modifier. After reading on another site some people have reported issues with the clutch packs. Is there a TSB about this issue and did I do the right thing by changing a like new fluid. I'll pick up the car tomorrow and the tech said the noise is gone. It's a independent shop not GM.
Le Mans Master
Joined: Dec 2006
Posts: 7,251
Likes: 16
From: Phoenix Arizona
too much modifier......drain it out and put in new rear end lubricant that has the modifier in it already. 
FYI you will get more answers in tech section or genral section on this kinda stuff
FYI you will get more answers in tech section or genral section on this kinda stuff
Thread Starter
Melting Slicks
Joined: Dec 2002
Posts: 2,061
Likes: 1
From: Valley Village CA
I don't know about having to much modifier. I was told by C4C5 specialist that the C5 diff is particular with certain brands of fluids and could chatter for some reason and did not like the Redline products. Drove the car to day after flushing with OEM fluids and 2 bottles of GM modifier the diff was very quiet now. I'll keep an ear out.
Le Mans Master
Joined: Dec 2006
Posts: 7,251
Likes: 16
From: Phoenix Arizona
i used royal purple and it worked great! not sure how good it is in an engine but in the tranny and rear end it really works well 
(FYI the ballbearing test they show for it is actually for gears not engines)
not sure how good it is in an engine but in the tranny and rear end it really works well (FYI the ballbearing test they show for it is actually for gears not engines)
Thread Starter
Melting Slicks
Joined: Dec 2002
Posts: 2,061
Likes: 1
From: Valley Village CA
I really can't be 100% sure if my diff did not like the redline products or not enough redline additive was used that's why I went back to OEM.I guess the only way to be totally sure is do it myself.Does Royal Purple diff fluid come with additive or did you add your own how many bottles and what brand.
Le Mans Master
Joined: Dec 2006
Posts: 7,251
Likes: 16
From: Phoenix Arizona
I really can't be 100% sure if my diff did not like the redline products or not enough redline additive was used that's why I went back to OEM.I guess the only way to be totally sure is do it myself.Does Royal Purple diff fluid come with additive or did you add your own how many bottles and what brand.
I THINK IT WAS A LITTLE LESS THAN 3 QUARTS ? 
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Le Mans Master
Joined: Dec 2006
Posts: 7,251
Likes: 16
From: Phoenix Arizona
Le Mans Master
Joined: Dec 2006
Posts: 7,251
Likes: 16
From: Phoenix Arizona
Thread Starter
Melting Slicks
Joined: Dec 2002
Posts: 2,061
Likes: 1
From: Valley Village CA
That makes me nervous using 2 bottles of modifier to shut it up VS your one bottle. Hopefully it's not the clutch packs time will tell.
Premium Supporting Vendor
Joined: Aug 2001
Posts: 5,364
Likes: 38
From: King George VA
Torched,
For what its worth, the AMSOIL Severe Gear Extreme Pressure Synthetic 75w90 contains friction modifier and I've never added extra in my 02 Z06 (or my 06 CTS-V which runs the same fluid) and I've never experienced chatter.
The C6 diff seems very susceptible to chatter and there are numerous TSBs out to add more friction modifier. For my C6 customers, I recommend adding one bottle of the AMSOIL Slip-Lock Differential Additive.
For the C5/C5 Z06, I recommend going with the straight Severe Gear 75w90, and only adding modifier if the diff chatters.
If yours isn't chattering right now, you are likely good to go.
For what its worth, the AMSOIL Severe Gear Extreme Pressure Synthetic 75w90 contains friction modifier and I've never added extra in my 02 Z06 (or my 06 CTS-V which runs the same fluid) and I've never experienced chatter.
The C6 diff seems very susceptible to chatter and there are numerous TSBs out to add more friction modifier. For my C6 customers, I recommend adding one bottle of the AMSOIL Slip-Lock Differential Additive.
For the C5/C5 Z06, I recommend going with the straight Severe Gear 75w90, and only adding modifier if the diff chatters.
If yours isn't chattering right now, you are likely good to go.
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